#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<math.h>
int main()
{
    double a = 0.0;
    double m = 0.0;
    double n = 0.0;
    double y = 0.0;
    scanf("%lf,%lf,%lf", &a, &m, &n);
    double t = log((m + n) / 2) / log(a);
    y = pow(pow(t, 2), 1 / 3.0);

    printf("%.2lf\n", y);
    return 0;
}